The program consists of 10 projects concerned with the organization of the spinal cord under normal conditions and in model states resembling human disease. In addition, there is an associated project supported by and R01 grant and several core facilities. The first 6 projects are concerned with pain mechanisms. Project 1 examines the detailed synaptic connectivity in the dorsal horn by stereological techniques, both in normal animals and after dorsal rhizotomy. Project 2 will investigate possible changes in chemically identified synaptic connections to identified spinothalamic tract neurons in a model of neuropathic pain. Project 3 also involves an analysis of changes in chemically identified synaptic connections spinothalamic neurons, but in acute arthritis. Project 4 is a biophysical study of the effects of excitatory amino acids and neuropeptides on identified trigeminothalamic neurons in a slice preparation. Project 5 is an effort to improve the classification of nociceptive and other neurons at different levels of the somatosensory system; this will facilitate comparisons of neuronal populations in normal and disease states. Project 6 is concerned with substances that are released in the spinal cord in response to noxious stimuli or activation of descending analgesia systems. The associated R01 project will interrelate with all of these projects by providing analyses of changes in the activity of spinothalamic neurons under comparable experimental conditions. Project 7 involves measurements of substances that are released in the spinal cord due to spinal cord injury. Project 8 is a study of the influence of nerve growth factor and antibodies to nerve growth factor on sprouting of primary afferent neurons. These projects have bearing on changes that affect pain transmission in nervous system disease and also on motor dysfunction. The remaining 4 projects are more directly related to motor and autonomic systems. Project 10 is an investigation of the membrane effects of excitatory amino acids on motoneurons in vitro. Project 12 investigates the organization of sacral parasympathetic neurons in relation to bladder control. The core facilitates include administration, a central computer facility, a light microscopy facility, an electron microscopy facility, an electronics shop, and a molecular biology laboratory.